With advancement in computer-based technologies, such as data communications (including wireless communication), the interconnectivity of multiple electronic devices in data communications systems has become a priority for the manufacturers and users of these system components. Devices such as, for example, PCs, video cameras, radio transmitters, and modems are required to work together, with the help of various adapters, processors, routers, and interfaces, for the efficient and effective operation of the data communications system. Due to the large number of hardware manufacturers, software developers, and service providers, this interconnectivity may be challenging or even prohibitive when assembling a data communications system.
In an effort to provide a compact, powerful, and adaptable format for PC-compatible devices, a standard was developed to use small (3.6″×3.8″), self-stacking 104-pin modules to allow for power sharing and communication between the modules. The format, known as PC/104 (based on its PC architecture and 104-pin configuration), established standards for mechanical pin and socket configurations and software used, as well as dimensional and electrical parameters, thus facilitating the combination of multiple modular devices into a relatively small and compact (0.6″ between device circuit boards), embedded interactive system, to support, for example, a wireless communication system.
FIG. 1A illustrates a side schematic view of an exemplary stack 10 of PC/104 based modules, including three different (but compatible) types of PC/104 architecture. The exemplary stack includes one 8-bit PC/104 module 20a, one 16-bit PC/104 module 20b, and one 32 bit PC/104-Plus module 20c. Each module 20a, 20b, 20c includes a printed circuit board 22 carrying a device 25, such as, for example, a modem, router, transmitter, or processor. The modules are connected with each other by pin and socket connectors. The 8-bit PC/104 module 20a includes a 64-pin ISA bus connector 26a, the 16-bit PC/104 module 20b includes a 104-pin ISA bus connector 26b, and the PC/104-Plus module 20c includes both a 104-pin ISA bus connector 26c and a 120-pin PCI bus connector 26c′, as shown more clearly in FIGS. 1B and 1C. Additionally, spacers 29 may be provided to add support to the modules and maintain proper spacing between the boards.
To connect the PC/104 stack 10 with an external device (not shown), such as, for example, a power or data source, one or more of the modules 20a, 20b, 20c are connected with the external device by way of the pin and socket bus connectors 26a, 26c, 26c′ of one of the end-most modules 20a, 20c of the stack 10, or by way of other or by some other connector extending from the module (not shown). As interconnectivity is provided between the stacked modules, only one of the modules may need to be connected to the external device.
While the self-stacking arrangement and limited external connectivity of the stack may make construction of such systems easier and more efficient, the manufacturer “bundling” of these modules may present difficulties with regard to end user modifications and servicing of any one or more of the modules. For example, maintenance or replacement of one module in the stack, particularly a module in the middle of the stack or a module to which an external device is connected, may require physical removal of the entire stack of modules and separation of devices from each other to perform such modifications. This may result in extended system downtime, maintenance hazards (particularly for systems in hazardous locations, such as utility poles), risk of improper reassembly, damage during disassembly/reassembly, diagnostic issues, and other difficulties. Even maintenance on an end-most module on a stack may require removal of the entire stack, due to space constraints within the enclosure that houses the stack. Further, even if maintenance of a module does not require removal of the stack, a network interruption of one or more of the remaining module devices may be necessary due to the data signal interconnectivity of all of the modules in the stack. This data signal interconnectivity may also result in potential bus signal conflicts between module devices in the stack, which may limit a user's options in adapting the assembly by replacing or adding electronic devices on the stack.